FS#544 - Investigate and support new RX1HS

DNP's introduced the RX1HS to replace the RX1. I'm told it's the same hardware, but requires different media.

Initial investigation shows it's added some features that were first introduced in the DS620. (iSerial support, maybe more). Backend changes will likely be minimal, but Gutenprint may require a tweak to expose any new features.

Further work will have to work until I get documentation or access to a printer.

Closed by Solomon Peachy
2016-10-07 02:01Reason for closing: ImplementedAdditional comments about closing:
Appears to be all-clear.